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Message-ID: <7f9fa4eb-01fb-4581-badf-535f634d0152@acm.org>
Date:   Tue, 24 Oct 2023 12:03:36 -0700
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Subject: Re: [PATCH] scsi: message: fusion: Fix a possible data race in
 mpt_ioc_reset()
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To:     Tuo Li <islituo@gmail.com>, sathya.prakash@broadcom.com,
        sreekanth.reddy@broadcom.com, suganath-prabu.subramani@broadcom.com
Cc:     MPT-FusionLinux.pdl@broadcom.com, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org, baijiaju1990@outlook.com,
        BassCheck <bass@buaa.edu.cn>
References: <20231024072729.455713-1-islituo@gmail.com>
From:   Bart Van Assche <bvanassche@acm.org>
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On 10/24/23 00:27, Tuo Li wrote:
> In my opinion, this may be a harmful race, because the value of
> ioc->taskmgmt_quiesce_io can be rewritten by mpt_ioc_reset() when
> another thread is accessing it.

It is a common pattern in the Linux kernel that a variable is set from
one thread without using locking and is read by another thread that is
holding a lock. It should be sufficient here to use WRITE_ONCE(). I
don't think that acquiring and releasing the spin lock is required.

Thanks,

Bart.